CEEN 341 - Lecture 10 - Effective Stress

This lecture introduces the principal of effective stress, which is arguably the most important principle in geotechnical engineering. Effective stress is derived, and a few examples showing the differences between total stress and effective stress are performed. The effect of groundwater seepage on effective stress is discussed.
Critical Questions to Consider:
1) How is effective stress different than total stress?
2) What is the critical assumption made regarding the area of the particle-to-particle contacts in deriving effective stress?
3) Why doesn't effective stress change when the elevation of surface water is adjusted? What would happen to effective stress if the elevation of groundwater increased? Decreased?
4) How does upward seepage affect effective stress? Why? What about downward seepage?

[@Hammer-w7x]

Ian 21 years experienced structural engineer and never understood the effective pressure properly before this video
Than you 👍

[@phanuong87]

one of the best channel for Civil Engineer!!. Thank you professor!. Can you also add lesson for slope stability?

[@SUJITKUMAR-kg5wh]

thanks for contributing the helpful re-sources free for us,In India coaching institutes loot millions of money from students for this kind of information.

[@marshmelows]

Amazing video and amazing explanation. Thank you so much Dr. Franke. This will help me in my thesis defense !

[@augustinngoumnai495]

The computation of pore pressures (Pp) seems to be incorrect.
This is what I think:
- at depht 10: Pp10=0
- at depht 50: Pp50= 60x62.4=3744 (using the piezometer)
As pore pressure behave linearly, the slope is (3744-0)/(50-10)=93.6
Therefore,
- at depht z, Pp(z)=93.6(z-10).
It gives:
Pp10=0
Pp20= 93.6x(20-10)=936
Pp50=93.6(50-10)=3744
Pp60= 4680.

[@TheAncientColossus]

SOMEONE ANSWER THIS.

[@bSMith266]

34:53, u20 and u60 cannot be computed like that as the seepage contribution cannot be determined by using the GWL head and Piezo head as a datum respectively. There are only two points to determine the PWP u10 and u50.

[@MasterCivilEngineering]

Step by step video solutions of civil engineering questions

[@mohammedelazrak1836]

Thank you sir .it's amazing axplanation

[@_Manic_Man]

So effective stress isn’t affected but depth of surfsce water? I thought if we lower groundwater table then effective stress decreases

[@rassolesmati421]

That was great explanation. Thank you .

[@harpergrace2510]

Don’t think your graphical representation of pore water pressure at 25:63 is right. Shouln’t you account the depth h in your triangle? Please correct me if I missed something, thanks!

[@ravipratap5811]

Sir plzzz add more as more lecture possible ...
Plzzzz......

[@abu-bakr9604]

What if you wanna get the more water pressure at C but you dont have a piezometer how will you find it?

[@futong6192]

Excellent lecture, thx!

[@MasterCivilEngineering]

True

[@czy46421]

Marvelous

[@Jefferson-uk6il]

What a Great Class!

[@tanooppersaud340]

does the piezometer have to be at a specific depth?

[@Meems458]

Thank you sir!! Good lecture!!

[@joshuajohnjulio]

I have a question at 34:51 why didnt you put piezometer at 20' below ground to determine the water rise and calculate the porewater pressure? is it just 10 x 62.4? tnx Godbless

[@harshitchauhan1792]

i have the same doubt

[@ahmedkamla2109]

Very well explained. Thank you.

[@mahmoudabdelmaksoud4895]

many thanks from egypt

[@the_right_path_14]

why is the piezometer indicates only the pore pressure has if there is only water in the tank ? (dosent the soil makes it diferent ? )

[@cschow2438]

Thank you. I love Geotech!

[@gh5030]

Very useful, thank you so much

[@diamondrush6944]

Thank you! Help a lot :)

[@rezakhomaini3167]

Very nice video sir!

[@kevinmanuel1836]

wow that was helpfull......now i love this subject😂

[@zs6511]

视频很好，谢谢！

[@ravipratap5811]

Mind blowing lecture sir

[@ujjwalmarasini9119]

In the calculation of pore water pressure down at 20', why is it used 10' but not 30'?

[@steebay]

because half (10') of the sand soil is dry and only half (10') is saturated. and we know to calculate pore pressure, we need only need the height of saturated soil.
hope that helps. in other words u use the height of the ground water table.

[@rayoaklight]

​@@steebay if we use bernoulli then it gives 30'

[@lisho6806]

Thank you Sir

[@wiltonjayguitap1921]

Mind blowing :)

[@MasterCivilEngineering]

Good

[@Ahmedmufty]

The lecture is nice but the definition or the expression to describe the effective stress as the contact to contact stress of particles is incorrect. The effective stress is a fictitious stress (not real stress) equal to the force transmitted by soil particles but divided by the total area of the soil cross section.

[@starmusic8597]

How can i take a matirial plz

[@Allumi]

tew gewd!

[@bale2935]

25:40
bless you sir

[@clinrden9378]

What's your reference in this lecture sir?

[@asmb1234]

Clinton Ordeniza "karun pa ko maglantaw" hindi mo kami malolokoooo

[@clinrden9378]

@@asmb1234 na-view na nako ni nga vid before pa gahatag si ma'am hahaha

[@joshuajohnjulio]

parang braja das xD

[@tluanga31]

12.21

[@mohdsalicarumpac8624]

Shout sa mga classmate ko sa 132 - moyaks

[@aldrinanthonytorres9107]

Go! Go! Na managan ta!
'Kay  anaa na ang ilang iro
Mamaghot, mama-ak, bisan unsa ka man kagahi
'Kay paakon niya labi na ang hambogero
Samong iro

[@czarlonlactuan8035]

hatag summary hehe

[@johnfelcambongga128]

Bossing